Custom Header property from sending to webhook event

[OnlyLeoo]

Hi,
I'm currently studying the integration of Postal in my application and I'd like to know, for mail sending via API, is it possible to add headers, will these same headers be rendered via WebHook?
The idea is to pass a specific ID to the header when sending and retrieve it in the webhook in order to associate the event with the mail in my application.
If need be, I could store the ID of the message returned by Postal and make the correspondence, but if I can use the headers, that would be convenient!

[willpower232]

If you're sending an email with the API then the response will include a Postal message identifier you can store and use in the future.

I don't think Postal would include your custom headers however if you aren't able to store the message identifier, presumably the webhook would include the message ID and you could re-ask Postal for the message which would probably do it. I'm not sure, I haven't really dived in to that side of the current API too much.